Wheel suspension system for a motor vehicle

ABSTRACT

The invention relates to a wheel suspension system for a motor vehicle, having a lower link for the fastening of a wheel which is coupled to a chassis underframe and is supported on the body via a spring. The chassis underframe is mounted on the body via elastic bearings and has an annular mounting on which the spring plate of the spring is supported before the wheel suspension system is installed. In the fitted state, the spring plate is pressed out of the mounting by the body and is therefore decoupled from the chassis underframe.

TECHNICAL FIELD

[0001] The invention relates to a wheel suspension system for a motorvehicle, containing a lower link for the attachment of a wheel, achassis underframe mounted on the body and a spring. The inventionfurthermore relates to a method for installing a wheel suspension systemof this type.

BACKGROUND OF THE INVENTION

[0002] In particular for the rear wheels of motor vehicles, individualwheel suspension systems are known, in which the wheels are attached toa “lower” (transverse) link. In order to damp the transmission of noisesand vibrations to the body, the lower link in this case is frequentlynot fastened directly to the body, but rather to a chassis underframe,(e.g., intermediate frame or auxiliary frame) which, for its part, isfastened to the longitudinal member of the body via rubber bearings.Furthermore, in the case of a wheel suspension system of this type, ahelical spring, the upper end of which is supported on the chassisunderframe via a spring, plate, is mounted on the lower link.

[0003] In the case of the conventional wheel suspension system describedabove, all of the forces transmitted between the wheel and body pass viathe chassis underframe, which constitutes a considerable load for therubber bearings thereof. For this reason, modifications of the wheelsuspension system are known, in which the spring is not supported on thechassis underframe by the spring plate, but rather is supported directlyon the body. The rubber bearings of the chassis underframe are therebynoticeably relieved of load. However, the installation of a wheelsuspension system of this type is problematical, since the spring isfree-standing before being installed on the separate wheel suspensionsystem. Only during the installation of the wheel suspension system isthe spring fitted onto the body (or alternatively, when pre-installed onthe body, to the lower link), in which case it is possible for thespring to become detached and injure the installers. Furthermore, duringfitting of the relatively long and stiff springs, the body is lifted offfrom the installation mountings. This also leads to a considerable riskof accident.

[0004] Against this background, it is desired to provide a wheelsuspension system with a spring which is supported on the body and whichis easier to fit.

SUMMARY OF THE INVENTION

[0005] The wheel suspension system according to the invention for amotor vehicle contains a link (or “lower link” below in accordance withthe installation position) which has means for the rotatable attachmentof a wheel. Furthermore, the wheel suspension system contains a chassisunderframe having bearings for fastening the chassis underframe to thebody of a motor vehicle. The link or lower link, in accordance with theinstallation position, is preferably connected to the chassis underframein an articulated manner. The chassis underframe typically extends overthe width of the vehicle, so that a wheel suspension system can beformed at both ends in each case. The wheel suspension system accordingto the invention furthermore contains a (helical) spring, the one end ofwhich (called “lower end” below in accordance with the installationposition) is arranged on the lower link and the other (“upper”) end ofwhich is covered by a spring plate. The wheel suspension system furtherincludes the chassis underframe having a mounting on which part of thespring plate is supported when the wheel suspension system is not (yet)fitted on the body of a motor vehicle.

[0006] The effect achieved by the mounting formed on the chassisunderframe and its interaction with the spring plate is that, even whenthe wheel suspension system is removed, the spring is not completelyfree-standing, but rather is securely clamped between the lower link andmounting of the chassis underframe. The installation procedure for awheel suspension system of this type can therefore essentially proceedin the same manner as in the case of wheel suspension systems in whichthe spring sits permanently (i.e. even in the fitted state) between thelower link and chassis underframe. Neither another configuration of theinstallation station nor a change of the installation sequence istherefore required. Since only part of the spring plate is supported onthe mounting, the exposed part of the spring plate can enter intocontact with the body during the installation and, when the finalinstallation position is reached, can take over the actual transmissionof force from the spring. This means that, in the fitted state, thespring plate is lifted off from the mounting of the chassis underframeand there is therefore no longer any coupling between the spring andchassis underframe, which has the advantages mentioned in relation torelieving the bearings of the chassis underframe from load.

[0007] The mounting which is attached to the chassis underframe ispreferably of annular design, so that said mounting can annularlysurround the spring plate and the latter can be supported by its (ifappropriate widened) edge on the mounting. A uniform, secure andcentered mounting of the spring plate on the mounting can thereby beachieved.

[0008] The spring plate is preferably provided with a centeringextension which, in the installation state, points in the direction ofthe body. With a centering extension of this type and a correspondingcentering hole on the body, it can be ensured that the spring“automatically” assumes a defined position on the body duringinstallation.

[0009] Furthermore, the spring plate can be combined with the support ofan additional spring (spring aid) in order to achieve a particularlycompact construction.

[0010] The bearings of the chassis underframe can be formed byelastomeric elements which ensure good damping of noises and vibrationswith respect to the body. The chassis underframe is preferably supportedon each side of the motor vehicle via two bearings, i.e. in total viafour bearings.

[0011] The lower link is preferably a transverse link.

[0012] The invention furthermore relates to a method for installing awheel suspension system comprising the following steps. First, having alower link for the attachment of a wheel, a chassis underframe having atleast one pair of bearings for fastening to a body of a motor vehicle,and a spring having a lower end and an upper end. The lower end of thespring is arranged on the link and the upper end of the spring isarranged in a spring plate. The chassis underframe has a mounting onwhich part of the spring plate is supported when the wheel suspensionsystem is not fitted on the body of a motor vehicle such that the springis supported on the mounting of the chassis underframe via the springplate. The spring is therefore not free-standing, and the wheelsuspension system is situated in a prepared, stable state. Second,fitting the wheel suspension system onto the body of a motor vehicle insuch a manner that the spring plate is supported on the body. This ispossible since the spring plate is only partially supported on themounting and therefore still has free contact surfaces for supporting onthe body. The positioning of the spring plate on the body is preferablyassisted by a centering extension on the spring plate and acorresponding centering opening on the body. Third, fastening thechassis underframe to the body of the motor vehicle, in which case thespring is compressed and the spring plate is lifted off from themounting of the chassis underframe. The fastening can take place, inparticular, with the aid of screw bolts.

[0013] The method described has the advantage that the wheel suspensionsystem can be fitted essentially in the manner of a conventional wheelsuspension system in which the spring is permanently supported on thechassis underframe. Nevertheless, owing to the spring plate lifting offfrom the mounting in the third step, in the fitted state, a directcoupling of force between the lower link and body is achieved, in whichcase the spring is independent of the chassis underframe.

[0014] In the method, the chassis underframe and the spring plate arepreferably attached to or mounted on a longitudinal member of the body,so that the wheel, forces are introduced into the body in a particularlyuniform manner.

[0015] With the provision of the wheel suspension system in first step,said system is preferably situated in an installation aid, so that thewheel suspension system can be securely handled. In this case, theinstallation aid has to permit the wheel suspension system to lift up asit is being fitted onto the body in the second step.

[0016] Other advantages and features of the present invention willbecome apparent when viewed in light of the detailed description of thepreferred embodiment when taken in conjunction with the attacheddrawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will be explained in greater detail below by way ofexample with the aid of the figures, in which:

[0018]FIG. 1 shows an exploded illustration of the wheel suspensionsystem according to the invention;

[0019]FIG. 2 shows a schematic section through the wheel suspensionsystem at the beginning of the installation;

[0020]FIG. 3 shows a section corresponding to FIG. 2 in an intermediatestage of the installation;

[0021]FIG. 4 shows a section corresponding to FIG. 2 at the end of theinstallation, and

[0022]FIG. 5 shows a section through the finally fitted wheel suspensionsystem perpendicular with respect to the direction of the section ofFIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023]FIG. 1 shows an exploded illustration of the wheel suspensionsystem according to one embodiment of the invention. Said wheelsuspension system essentially comprises a chassis underframe 1, only oneend of which is illustrated in the figure. The chassis underframe 1extends over the width of a motor vehicle and is of mirror-symmetricaldesign at both ends. At the illustrated end of the chassis underframe 1,a pair of rubber bearings 2 can be seen via which the chassis underframe1 is mounted on the body of a motor vehicle (not illustrated in FIG. 1)and can be fastened there with the aid of screw bolts 4 having a widehead.

[0024] The wheel suspension system furthermore comprises a lower link 10which supports (in a manner not illustrated specifically) the wheelwhich is to be suspended. In the pre-fitted state of the wheelsuspension system, the link 10 is coupled by its end which is on theright in the figure to the chassis underframe 1 in an articulatedmanner. Furthermore, the link 10 has a widened section with a depressionin which the lower end of a helical spring 9 is mounted.

[0025] The helical spring 9 is supported by its upper end on the lowerside of a spring plate 6 with the connection in-between of an insulationring 8. In the pre-fitted state of the wheel suspension system, thewidened edge of the spring plate 6 bears with its upper side against anannular mounting 3 which is integrally formed on the chassis underframe1, so that the spring 9 is fixed between the lower link 10 and chassisunderframe 1 in a pre-stressed state.

[0026] A centering extension 5 on the upper side of the spring plate 6and a spring aid 7 which is secured on the lower side of the springplate 6 can furthermore be seen in FIG. 1. Such a dual function of thespring plate 6 as a support for the spring 9 and for the spring aid 7is, however, not absolutely necessary, since the spring aid 7 may alsobe supported at a different point, for example on a supporting bar (notillustrated), of the wheel suspension system.

[0027]FIGS. 2, 3 and 4 each show a schematic section in the longitudinaldirection of a motor vehicle through the wheel suspension systemaccording to the invention and through the longitudinal member 11 of themotor vehicle in consecutive stages of the installation. The samereference numbers as in FIG. 1 represent the same parts, so they willnot be explained again.

[0028]FIG. 2 illustrates the first step of the installation of a wheelsuspension system according to the invention on a motor vehicle. Thepre-fitted wheel suspension system is provided on an installation aid(not illustrated) on which said system is secured over the chassisunderframe with securing means such as “C-hooks”. Since the spring 9supports the edge of the spring plate 6 on the mounting 3 of the chassisunderframe, there is no free-standing spring which could lead toproblems during the installation. The annular mounting 3 of the chassisunderframe secures the arrangement, comprising the spring plate 6, whichalso includes the support for the spring aid, and the insulation ring 8,in a centered position and prevents it from falling apart.

[0029] The installation is therefore continued in that the installationaid lifts off the wheel suspension system in the direction of the arrowstoward the body, of which the longitudinal number 11 is indicated. Inthis case, a pre-setting of the position of the axis with respect to thebody can take place via installation pins.

[0030]FIG. 3 shows an intermediate stage of the installation process inwhich the centering extension 5 has found the associated hole, which issurrounded by a flange, in the longitudinal member 11 and, as it passesthrough it, has thereby centered the wheel suspension system. Theautomatic centering of the wheel suspension system enables rapidinstallation without risky manual interventions to take place. In theillustrated state, the wheel suspension system has been lifted upprecisely until the upper side of the spring plate 6 comes into contactwith the lower side of the longitudinal member 11. At this moment, thescrew bolts 4 are also pushed through corresponding holes in the rubbersleeves 2 of the chassis underframe and are screwed into the associatedthreads on the longitudinal member 11. There is initially still a gapbetween the rubber sleeves 2 and the longitudinal member 11.

[0031]FIG. 4 shows the end of the installation process. The bolts 4 havebeen tightened against the weight of the wheel suspension system and theclamping force of the spring 9 and have been completely screwed intotheir threads, in which case they press the wheel suspension systemagainst the longitudinal member 11 and close the previously existing gapbetween the rubber sleeves 2 and the longitudinal member 11. Animportant feature is that, when the chassis underframe is lifted up, itsmounting 3 is lifted off from the spring plate 6, which is secured bythe longitudinal member 11. There is therefore no longer any couplingbetween the spring 9 and the chassis underframe.

[0032] Since, with the tightening of the screw bolts 4 to a desiredtorque, the installation is finished, the installation aid andadditional tool (not illustrated) can be removed. An advantageousfeature of the installation process is that it can be executed in aconventional installation station and with the known installation steps.

[0033]FIG. 5 shows a cross section through the finally fitted wheelsuspension system in a direction perpendicular to the sections of FIGS.2 to 4. The spring aid 7 can additionally also be seen on the wheelsuspension system in this case.

[0034] The wheel suspension system according to the invention thereforeenables a direct coupling (in the fitted state) of the lower link 10onto the body 11 without this leading to problems or risks during theinstallation. This result is achieved by the mounting 3 on the chassisunderframe 1, said mounting receiving the spring 9 in the pre-fittedstate of the wheel suspension system.

[0035] While particular embodiments of the invention have been shown anddescribed, numerous variations and alternate embodiments will occur tothose skilled in the art. Accordingly, it is intended that the inventionbe limited only in terms of the appended claims.

What is claimed is:
 1. A wheel suspension system for a motor vehicle,comprising: a lower link for the attachment of a wheel; a chassisunderframe having at least one pair of bearings for fastening to a bodyof a motor vehicle; and a spring having a lower end and an upper end,the lower end of which is arranged on the link and the upper end ofwhich is arranged in a spring plate; wherein the chassis underframe hasa mounting on which part of the spring plate is supported when the wheelsuspension system is not fitted on the body of a motor vehicle.
 2. Thewheel suspension system of claim 1, wherein the mounting annularlysurrounds the spring plate.
 3. The wheel suspension system of claim 1,wherein the spring plate has a centering extension.
 4. The wheelsuspension system of claim 2, wherein the spring plate has a centeringextension.
 5. The wheel suspension system of claim 1, 2, 3, or 4,wherein the spring plate is combined with the support of a spring aid.6. The wheel suspension system of claim 1, 2, 3, or 4, wherein at leastone pair of bearings of the chassis underframe are formed by elastomericelements.
 7. The wheel suspension system of claim 4, wherein the springplate is combined with the support of a spring aid and at least one pairof bearings of the chassis underframe are formed by elastomericelements.
 8. The wheel suspension system of claim 1, 2, 3, or 4, whereinthe lower link is designed as a transverse link.
 9. The wheel suspensionsystem of claim 4, wherein the spring plate is combined with the supportof a spring aid and the lower link is designed as a transverse link. 10.The wheel suspension system of claim 4, wherein at least one pair ofbearings of the chassis underframe are formed by elastomeric elementsand the lower link is designed as a transverse link.
 11. The wheelsuspension system of claim 7, wherein the lower link is designed as atransverse link.
 12. A method for installing a wheel suspension system,comprising the following steps: Providing a wheel suspension systemhaving a lower link for the attachment of a wheel, a chassis underframehaving at least one pair of bearings for fastening to a body of a motorvehicle, and a spring having a lower end and an upper end, the lower endof which is arranged on the link and the upper end of the which isarranged in a spring plate wherein the chassis underframe has a mountingon which part of the spring plate is supported when the wheel suspensionsystem is not fitted on the body of a motor vehicle; Fitting the wheelsuspension system onto the body of a motor vehicle so that the springplate is supported on the body; and Fastening the chassis underframe tothe body of the motor vehicle, the spring being compressed and thespring plate lifting off from the mounting of the chassis underframe.13. The method of claim 12, wherein the chassis underframe and thespring plate are mounted on a longitudinal member of the body.
 14. Themethod of claim 12 wherein the wheel suspension system is provided in aninstallation aid.
 15. The method of claim 13, wherein the wheelsuspension system is provided in an installation aid.